The present invention relates generally to a fire ring. More particularly, the present invention relates to spring back fire ring wherein the distal end of the fire ring serves as a spring washer to follow the cylinder head movement during the operation of the engine.
Gaskets are often used as seal between mating metal surfaces. One common application involves the placement of a gasket between a head and an exhaust manifold of an internal combustion engine. Such gaskets are considered high temperature gaskets since they provide a seal, which prevents the byproducts of combustion exiting the engine from escaping into the engine compartment of a vehicle.
One typical problem that occurs with such gaskets is insuring effective sealing, especially where xe2x80x9cthermal pushxe2x80x9d occurs, i.e., where an improperly cooled zone of the engine, such as the head, will grow as the result of overheating and then excessively compress the sealing means, such as a fire ring. While the gasket will seal effectively under excessive compressive loads, once the engine cools down, the sealing effect of the gasket in the excessively compressed areas may be lost. Upon subsequent use of the engine, the gasket area that had been excessively compressed will not seal until the area becomes overheated. Accordingly, the gasket will not properly seal, resulting in a significant loss of compression and power, which may lead to long term damage to the engine.
Various attempts have been made to prevent improper compression resulting from thermal push. For example, metal shims have been used. However, the shims require precise positioning. Another attempt includes the use of a metallic plate head gasket with embossments around the combustion opening. However, metallic plates require specific attachments and also require additional openings that must mate properly with coolant openings and the like.
Another attempt to prevent improper compression has been to employ a fire ring bonded on the end of the main gasket body at the combustion openings. The fire ring includes annular feet to properly seat the fire ring between the cylinder block and the cylinder liner. To provide adequate sealing, the prior art fire ring straddles the cylinder block and cylinder liner to seal the combustion gases, with at least one sealing foot on the cylinder block and one sealing foot on the cylinder liner. However, because the fire ring is bonded to the main gasket body, additional manufacturing steps must be taken, thereby increasing production costs. Moreover, there is nothing to insure that the fire ring will follow the cylinder head movement during operation of the engine after being subjected to excessive heat.
Accordingly, there exists a need for an improved, low-cost fire ring that achieves reliable sealing for combustion bore openings.
The present invention is directed to a gasket assembly for sealing mating components in an internal combustion engine that includes an improved low-cost spring back fire ring. In accordance with the invention, the gasket assembly includes a main gasket body that has at least one combustion opening, and at least upper and lower gasket layers with combustion openings that generally correspond to the combustion opening formed in the main gasket body and a spring back fire ring. The spring back fire ring is positioned in the aligned combustion openings of the main gasket body and the gasket layers.
The spring back fire ring has first and second ends. In accordance with the invention, the first end is biased upwardly from the second end. The upwardly biased first end allows the spring back fire ring to follow the cylinder head movement during operation of the engine for improved sealing around the periphery of the combustion openings. The second end of the spring back fire ring is positioned proximate to the periphery of the main gasket body. In one preferred embodiment, the second end of the spring back fire ring is integral with the main gasket body such that the main gasket body and the spring back fire ring are formed as a one-piece constant material member. Forming the main gasket body and the spring back fire ring from a single material advantageously serves to eliminate a manufacturing operation.
The spring back fire ring may also be provided with control beads. Preferably, a first control bead is provided that extends upwardly from a top surface of the spring back fire ring and a second control bead is provided that extends downwardly from a bottom surface of the spring back fire ring spaced laterally from the first control bead. The opposing and laterally spaced control beads provide additional sealing for the spring back fire ring.